1. Field of the Invention
The present invention relates to an anti-roll bar device, and more particularly to an anti-roll bar device with a variable rigidity.
2. Description of Related Art
When a vehicle is in cornering, a centrifugal force will lead to a vehicle body of the vehicle to tilt, and the vehicle may be capsized easily, so an anti-roll bar device is mounted between two suspension systems of two wheels, and two ends of the anti-roll bar device are mounted on bottoms of the suspension systems. Multiple fixing units are mounted on the anti-roll bar device and are fixed on the vehicle body, such that the anti-roll bar device can be fixed on the vehicle body.
When the vehicle is in cornering, the vehicle is tilted due to the centrifugal force, and the suspension systems will be forced. The suspension system which is located at an outer side of the vehicle will be compressed, and the other suspension system which is located at an inner side of the vehicle will be extended, so a height difference is formed between the two suspension systems. The suspension systems respectively exert torques on the two ends of the anti-roll bar device, so the anti-roll bar device will generate an upward force for the suspension system which is located at the inner side of the vehicle, and generate a downward force for the suspension system which is located at the outer side of the vehicle to decrease the height difference. Tilting of the vehicle can be avoided so as to decrease risk of capsizing for the vehicle.
However, when the vehicle passes a bumpy terrain, a slight height difference is continuously formed between the two suspension systems because of the bumpy road conditions. If the vehicle does not have the anti-roll bar device, the vehicle body will tilt or shake up and down. If the vehicle has the anti-roll bar device, the anti-roll bar device can keep the vehicle body from tilting, but the vehicle may still shake up and down, causing discomfort of motorists and passengers.